This invention relates to a multi-level high-voltage ultrasound transmit pulser integrated circuit for medical ultrasound scanning image system, and more particularly, to an array of high voltage switches for a high-voltage output pulse generator for exciting the piezoelectric or capacitive-electrostatic elements in the ultrasound transducer probe in an ultrasound medical B-scan and a color image system.
Ultrasound medical imaging applications have a growing demand for more sophisticated excitation waveforms and sequential scanning methods for large number of piezoelectric or capacitive-electrostatic element arrays. The commonly used ultrasound transmit pulse generator generally consists of three or more pairs of P-type and N-type high voltage power MOSFETs driven by a very fast and powerful gate driver circuit. Each channel of the pulse generator needs to produce high voltage and high current to charge or discharge the load capacitance at ultrasound frequency or speed. The load capacitance of the piezoelectric or capacitive-electrostatic elements and the cable equivalent capacitance together usually are quite large, and the ultrasound frequency is in 1 to 20 MHz or higher frequency range. The transmitter pulser requires large output current; therefore it requires large MOSFET sizes. The advanced color Doppler ultrasound imaging systems further require that the waveform generated from this pulse generator contain multiple voltage-levels, in clouding the zero-level or near zero voltage levels. Further each IC has to built-in multiple channels of pulse generators. For examples, the dual, quad, octal-channel, even 16 or 32 channels need to be built-in one IC package.
Therefore, it would be desirable to provide a system and method that overcomes the above issues. It would further be desirable to provide a high-voltage transmit pulse generating circuit topology and method that uses the lower-voltage, low-cost but high-current, higher-speed large scale integrating semiconductor process.